The additive manufacturing process is widely known as the three dimensional printing of 3D objects. Numerous methodologies have been described in prior art, the most common including solid-laser-sintering (“SLS”), stereolithography (“SLA”), and extrusion based 3D printing or FFF (fused filament fabrication). Extrusion-based 3D printing involves the deposition of thermoplastic materials. Prototyping is the most common application of extrusion-based printing today, using materials such as ABS (acrylonitrile butadiene styrene) and PLA (polylactic acid). Further, the technologies have progressed to where the 3D printing also utilizes higher-end engineering semi-crystalline and amorphous polymers as well as metals and ceramics with greater mechanical, chemical, thermal and electrical properties. Examples of semi-crystalline polymers include polyetheretherketone (PEEK), polyetherketoneketone (PEKK), etc. Examples of amorphous engineering polymers include polyphenylsulphone (PPSU), polyetherimide (PEI), etc.
Prior art for extrusion based 3D printing teaches extruding the filament through an extruder and depositing the extrudate on a build platform, a layer at a time to form a 3D object in open loop with no feedback concerning the build process or quality of deposition. As a result, defects in the 3D object printing lead to one or more errors in its geometry (i.e. dimensions or contours) or deficiencies in desired properties (e.g. mechanical, chemical, thermal, or electrical properties).
These defects, errors, or characteristics that depart from the intended design, due to deviation in filament diameter, filament feed rate, nozzle orifice, result in inaccurate volume of extrudate deposition; inaccuracy in the print head to follow the desired tool path causing out of tolerance features; deviation in heating or cooling temperature of the deposited material resulting in defects such as drooping/sagging, reduced crystallinity, slow solidification, air bubbles, delamination, overhangs, warping, or poor adhesion between printed layers of the object or the build plate. Hence, these defects if not corrected, lead to flaws, such as insufficient mechanical, chemical, thermal, or electrical properties, in the printed object.
One of the 3D printing methods used is illustrated in FIG. 1. A slicing software slices a 3D object file (100) into a number of layers (102) using slicing parameters such as filament diameter, nozzle orifice, layer thickness, fill ratio, print head speed etc. Tool path instructions (104) are generated for each layer and are fed to a 3D printer where each layer is printed without any means to monitor, detect or correct errors or modify slicing parameters based on analysis of printed layers. If the printing of the layers to build the object is finished (106), the printing stops (108). Otherwise, the method loops back to printing next layer by the extruder (104).
The prior art do not disclose providing a quantitative and qualitative report that may inform a user of the 3D printing process about the structure of the printed object along with the features of the defects and further, guide the user to keep or scrap the object. Also, such reports guiding in improving the printing of three dimensional objects are lacking in the prior art.
Therefore, there exists a need in three dimensional printing methods for monitoring and identification of defects formed in a 3D object while it is being printed, and further, in-situ correction of the defects in the object simultaneously as the object is being printed. There also exists a need for a closed-loop slicing engine that updates the slicing parameters and object model in-situ, based on the defect data and object geometry. Furthermore, there exists a need in three dimensional printing for developing a report displaying geometry and the features of corrected and uncorrected defects in the 3D printing processes for improvement in the printing.